Smelting-furnace, particularly for the production of steel



Dc. 6', 1966 I J. MAATcH ETAL SMELTING-FURNACE, PARTICULARLY FOR THEPRODUCTION OF STEEL Filed July 1 6, 1965 4 Sheets-Sheet 1 .7nventors IRa.

Dec. 6, 1966 MAATSCH ETAL 3,290,031

FURNACE, PARTICULARLY FOR THE PRODUCTION OF STEEL SMELTING- Filed July16, 1963 4 Sheets-Sheet 2 Dec. 6, 1966 MAAT H ETAL 3,290,031

SMELTING FURNACE, PARTICULARLY FOR THE PRODUCTION OF STEEL Filed July16, 1963 4 Sheets-Sheet 3 Dec. 6, 1966 J. MAATSCH ETAL 3,290,031

SMELTING-FURNACE, PARTICULARLY FOR THE PRODUCTION OF STEEL Filed July16, 1963 4 Sheets$heet United States Patent ,790 Claims. (Cl. 266-11)The present invention relates to a smelting-furnace, particularly forthe production of steel from scrap iron and carburization material,which is heated by means of burners for gaseous, liquid or powdery fueland oxygen or air enriched with oxygen and in which the discharge of thegases takes place through an opening of the furnace arch over which amovable, for instance, rollable or swingable flue is disposed.

Such smelting furnace for the production of steel from scrap iron andcarburization material adapted for heating with gaseous, liquid forpulverized fuel with oxygen or oxygen enriched air has been disclosed inthe co-pending patent application, Serial No. 264,635, filed March 12,1963 now Patent No. 3,188,065.

The present invention is based on the discovery that the furnacedescribed in said copending patent application, Serial No. 264,635, isparticularly suitable for all steel production methods combined with afining process and in particular also for such methods, in which thefining takes place by blowing of oxygen and/ or in which the reductionis performed with a slag poor in FeO, in such manner, as it isconventional in an arc furnace.

It is, therefore, one object of the present invention to provide asmelting furnace, particularly for the production of steel, wherein thisgeneral applicability of the furnace designed in accordance with thestructure disclosed in said copending patent application Serial No.264,635 is brought about in such manner, that the furnace is heatedselectively by means of burners or by means of electrodes.

It is another object of the present invention to provide asmelting-furnace, particularly for the production of steel, wherein thesmelting and fining is performed by means of burner heating and thereduction by means of heating with electrodes. During the fining, oxygencan be blown onto the bath, and in particular, either the burner orpredetermined burners can be used for the blowing of the oxygen orparticular nozzles are provided for this purpose. Practically allspecialties of steel can be produced in this furnace and also suchspecialties, in which particularly high requirements are put on thequality, as for electric steel, since the reduction of the steel takesplace by means of heating the melt with electrodes. The reduction can beperformed in the same manner as in an electro furnace with slag poor inFeO.

It is still another object of the present invention to provide asmelting-furnace, particularly for the production of steel, wherein themelts are produced in the furnace such, that the furnace is fed in amanner conventional with an open hearth furnace method with scrap ironand pig iron serving as carburization material and the charge is moltenby means of burners operated with fuel and oxygen. The decarburizationand the dephosphorizing can take place, as it is conventional, inconnection with open hearth furnaces, by means of the oxydizing flameover the slag. It is also possible, however, to perform the fining stepwith oxygen, which is blown onto the bath and which reacts directly withthe melt.

Patented Dec. 6, 1966 It is still another object of the presentinvention to provide a smelting furnace, particularly for the productionof steel, wherein the furnace is fed with liquid pig iron and the latteris subjected to a fining step with oxygen, as in an LD-converter,whereby more scrap iron is added, as it would be done in the normalLD-process, because the heating of the furnace makes possible thefeeding of heat for the melting of the scrap iron in larger quantities.After the fining step, and under circumstances upon tapping thedephosphorizing slag, the reduction can then be performed with new slagand with heating of the melt by means of electrodes.

With these and other objects in view, which will become apparent in thefollowing detailed description, the present invention will be clearlyunderstood in connection with the accompanying drawings, in which:

FIGURE 1 is a elevation, partly in section, of a melting furnace withswung out electrodes, in case of burner heating; a

FIG. 2 is an elevation, partly in section, of the furnace shown in FIG.1, indicating the position in case of electrode heating;

FIG. 3 is a top plan view of two melting furnaces designed in accordancewith the present invention;

FIG. 4 is an elevation of one of the furnaces shown in FIG. 3, seen fromthe tapping side in case of operation with burners; and

FIG. 5 is an elevation of one of the furnaces shown in FIG. 3 seen fromslag-out side in case of operation with electrodes.

Referring now to the drawings, and in particular to FIGS. 1 and 2, thefurnace comprises a circular furnace vessel 1 which is equipped with acentral head burner 2 and which includes a hearth 3 receiving thecharge, which is molten by means of the central head burner 2. Thefurnace vessel 1 is tippingly mounted on the rocker 5. A furnace arch 6is exchangeably mounted on top of the furnace vessel 1 and has a centralopening 7 (FIG. 1), through which the furnace gases are discharged intothe gas flue 8 and are fed into a waste heat vessel 9. In addition tothe central burner 2, tiltingly disposed lateral burners 12 areprovided, which can be lifted and lowered, respectively, in the samemanner as the central burner 2, which lateral burners 12 can be adjustedin their position during the melting period to the prevailing surface ofthe melting charge. The burners 2 and 12 can be used selectively alsofor blowing-on of oxygen onto the melt, whereby the fuel feed is closedcompletely or partly, so that free oxygen can be fed to the bath with aquantity of 15 Nm. /t.u.min. preferably about 3 Nm. /t.u.min. One or aplurality of doors 13 and an inspection hole 15 for the observation ofthe melt are provided in the furnace vessel 1. False air is sucked intothe furnace by means of channels 16 which are equally distributed aboutthe periphery of the furnace, which false air cools the arch 6. The flue8 is swingable by means of a swingable column 19. A

swingable lifting cylinder 20 is disposed adjacent the furnace, whichlifting cylinder 20 serves the purpose of swinging in and out,respectively, the arch lid 6' (FIG. 2) and the electrodes 22, includingtheir carrying device 23 by means of a swinging arm 21. The feed ofelectric current to the electrodes 22 takes place by means of thecurrent rails 25 and flexible conduits 24.

If a shifting takes place from the burner heating to the electrodeheating, at first the burners 2 and 12 are lifted into an upper positionby any conventional means and the flue 8 swings out into the positionshown in FIG. 2 of the drawings. Then the swinging arm 21 together withthe electrodes 22 and the arch lid 6 swing over the furnace and the archlid 6' is set over the opening 7 of the arch 6 and the electrodes 22 arerolled in. Upon 3 shifting to burner heating, the same movements takeplace in reversed succession.

Referring now again to the drawings, and in particular to FIG. 3, twofurnaces are disclosed designed in accordance with the presentinvention, which are coupled together' such that the burners and theelectrodes can be exchangeably used for both furnaces. This has theadvantage, that the voluminous device for the electrode operation isbetter exploited and that the rest and cooling occurring during theburner heating, which reduces the wear on the electrodes, is avoided andshortened, respectively.

The two furnaces 31 and 32 are arranged in such mannet, that they can betapped into a ladel car 33 which is rollable on the tracks 34. Slagbuckets 33 and 36 are arranged on the opposite sides on the furnaces 31and 32. In accordance with the present invention, a single gas flue 37is provided for both furnaces and only one swinging frame 38 is arrangedfor the electrodes 39. A saturation device and a dust separator 42 aredisposed on the swinging arm 41 arranged on the swinging column 40 forthe gas flue 37, from which saturation device and dust separator 43 arefed off the gases through the conduit 43, which is rotatable relative tothe conduit 43' (FIG. 4). The electrodes 39 are swingable from onefurnace to the other by means of the swinging frame 38, which isrollable on a track 44.

Referring now again to the drawings, and in particular to FIGS. 4 and 5,a working platform 45 is provided. Both furnace vessels 31 and 32 arenot only tiltable on the rockers 46 and 47, but are mounted alsorotatably on the rotary devices 48 and 49. The rotation of the furnacevessels should accelerate the melting of the charge. Since the furnacearohes 50 and 51 do not join the rotation, it is possible to reach theentire hearth with the burner flames by a corresponding arrangement ofthe burners 52 (FIG. 4) on the swinging arm 41 at different distancesfrom the rotating axis of the furnace vessel.

As can be ascertained from FIG. 5, the electrode carrying frame 53 isdisposed on the swinging frame 38. A transformer 54, which is likewiseoperative for both furnaces, swings with the swinging frame 38, wherebythe latter is supported by the rolling track 44. The dimensioning of thetransformer can take into consideration, that it is designed not for thehigh current requirement for the melting, but for the appreciably lessercurrent requirement in the fining period. The current is fed to theelectrodes 39 by flexible electrical conduits 55. The furnace arch 50,as well as the lid 56 closing the discharge opening, are suspended fromthe swinging frame 38 for a lifting and lowering movement.

While in the positions of the swinging frames 38 and 40 shown in FIG. 3of the drawings, the furnace 31 performs a fining operation, the chargeis either molten in the furnace 32 by means of the burners 52, or themelt is subjected to fining with oxygen, which is blown thereon throughthe burners 52 or by means of particular oxygen nozzles. If the devicesare to be exchanged after tapping of the fined melt of the furnace 31into the container 33, the swinging arm 41 is shifted from the positionshown in full lines into the position indicated in dash-pointed lines asB in FIG. 3 of the drawings, whereby the path for the swinging frame 38is freed, so that now the swinging frame 38 swings from the positionindicated by A as far over the position A indicated in dash-pointedlines, that upon filling the furnace vessel 31 with scrap iron and withliquid pig iron, respectively, the swinging arm 41 together with theburners 52 can be brought into the position B above the furnace vessel31. Thereafter, the

swinging arm 38 is brought into the swinging position A 7 While we havedisclosed several embodiments of the 4 present invention, it is to beunderstood that these embodiments are given by example only and not in alimiting sense, the scope of the present invention being determined bythe objects and the claims.

We claim: 1. A smelting furnace, particularly for the production ofsteel, comprising a furnace vessel, an arch having an opening supportedby said furnace vessel, said opening in said arch being adapted todischarge gases from said furnace vessel, burner means disposed in theupper portion of said furnace vessel for heating the latter, a fluemovably disposed on top of said arch, said burner comprising fuelburners and electrode burners, the latter including a transformer, to beused selectively and exchangeably, and said electrode burners extendingthrough said opening in said arch. 2. The smelting furnace, as set forthin claim 1, which includes means for rolling said flue-from itsoperative, arch covering position into its lateral inoperative position.3. The smelting furnace, as set forth in claim 1, which includes meansfor swinging said flue from its operative, aroh covering position intoits lateral inoperative position. 4. The smelting furnace, as set forthin claim 1, which includes means for fining melt formed in said furnacevessel including means for feeding oxygen to said melt. 5. The smeltingfurnace, as set forth in claim 1, which includes a first swinging devicecarrying said electrode burners,

and a second swinging device carrying said movable flue. 6. The smeltingfurnace, as set forth in claim 5, wherein said first swinging devicecarries said electrode burners and said transformer. 7. The smeltingfurnace, as set forth in claim 5, which includes a lid covering saidopening of said arch and being suspended from said first swinging devicefor a lifting and lowering movement, respectively. 8. The smeltingfurnace, as set forth in claim 5, wherein said second swinging devicecarrying said movable flue supports simultaneously said fuel burners. 9.The smelting furnace, as set forth in claim 1, which includes means forcoupling said furnace with an equal second furnace, and said electrodeburners and said transformer selectively heating one of said furnaces.10. The smelting furnace, as set forth in claim 9, wherein said flue andsaid fuel burners are operatively connected selectively with one of saidfurnaces.

References Cited by the Examiner UNITED STATES PATENTS 2,927,142 3/1960LaBate 132 3,188,065 6/1965 Hoffman et al 263-33 3,197,539 7/1965 Hindsl39 3,207,596 9/1965 Pinches --1l DAVID L. RECK, Primary Examiner.

H. F. SAITO, Examiner.

1. A SMELTING FURNACE, PARTICULARLY FOR THE PRODUCTION OF STEEL,COMPRISING A FURNACE VESSEL, AN ARCH HAVING AN OPENING SUPPORTED BY SAIDFURNACE VESSEL, SAID OPENING IN SAID ARCH BEING ADAPTED TO DISCHARGEGASES FROM SAID FURNACE VESSEL, BURNER MEANS DISPOSED IN THE UPPERPORTION OF SAID FURNACE VESSEL FOR HEATING THE LATTER, A FLUE MOVABLYDIDPOSED ON TOP OF SAID ARCH, SAID BURNER COMPRISING FUEL BURNERS ANDELECTRODE BURNERS, THE LATTER INCLUDING A TRANSFORMER, TO BE USEDSELECTIVELY AND EXCHANGEABLY, AND SAID ELECTRODE BURNERS EXTENDINGTHROUGH SAID OPENING IN SAID ARCH.